Fuel pump



L.. o. HEDBLOM FUEL PUMP Nov. 16, 1937.

Filed Feb. 18, 1935 2 Sl'Leets--SheeI 2 BY A/ /fff' 7197 ATTORNEYS CII Patented Nov. i6, i937 UNITED STATES PATENT oFFlCE FUEL PUMP

Lars olafjeabiom, Detroit, Mich., assignor or I one-half to Gustav A.

Carlson, Detroit, Mich.

Application February 1s, 19'35, seal No. 6,988

2 claims.

relation thereto, and means between the operating cam and an injector mechanism which is subject tov manual adjustment to prevent operative performance of the injector mechanism when the engine is running on momentum after the throttle has been closed. To this end, the closing of the throttle effects an instantaneous adjustment in the injector mechanism whereby continued rotation of the cam shaft may take place as a result of momentum of the engine without resulting in a fuel pumping action in the injector.

Another object of the invention is to provide means for controlling successivey ejections of fuel from a fuel injector mechanism whereby successive injections of fuel into a cylinder of a combustion engine are definitely timed relative to movement of a piston in the cylinder so that the travel. '-I'he means for ejecting the fuel from the Y injector comprises a reciprocating plunger which y causes fuel to be injected into the cylinder of the engine with each pumping stroke thereof,

and the regulating means cooperates with the plunger and' provides a means for varying the length of thepumping stroke of the plunger so as to vary the size of the injection. In varying the length of the stroke two important functions are provided for by the invention. The first function is that the reciprocating plunger always starts its pumping stroke at the same point and the length of the stroke is varied by moving it different distances from this constant point: The other function is that the injection of the fuel is always terminated when the piston in the engine cylinder reaches a definite point in relation toits firing point and the length of the injection stroke is varied by starting it at various points in advance of the constant terminating point.

Another object of the invention is to provide a stroke adjuster which co-relates the movement of a plunger with an operating cam so that the (Cl. S-38) cam may be rotated without imparting movement to the plunger and so that rotation of the cam may be utilized to impart various amounts of movement to the plunger. In this connection, the stroke adjuster functions whereby a. short stroke of the plunger requires a short angular movement of the operating' cam and a longer stroke of the plunger requires a longer angular movement of the cam. For example, a full stroke of the plunger requires a certain number of de: grees of rotation of the cam whereas a half stroke requires movement of the cam through half that number of degrees. The advantage of this function is that thev time interval necessary to cornplete an injection is actually less in connection with a short injection than it is with .a longer injection even though the cam is rotating at a slower rate of speed, when the short injections are taking place', than it is when the longer ini jections are takingv place, with the result that the fuel injected at idling speed of the engine does not have sufficient time to expand to the extent that it bucks the engine. In other words, during short injections, the fuel is not injected too far in advance of the firing point to cause unnecessary back pressure on the piston dueto the natural tendency of the fuel to expand when it contacts the walls of the heated cylinder and piston whereby the start of the injection automatically advances as the volume of the injection increases. Still another object ofthe present invention is to provide a device for synchronizing the movements of an injector plunger, its operating cam and the `piston of an engine so that the plunger stroke terminates at a predetermined stage of rotation of theiopertaing cam and so that the predetermined stage of rotation of the operating cam is reached when the piston in the engine cylinder has reached a predetermined point in its travel, and for maintaining the synchronized relationship during adjustments to vary the length of the stroke of the plunger. Thus, three functions rernain in constant timed relation, the termination of the actuating movement of the 'cam `with respect to the plunger, the point from which the plunger pumping stroke starts, and the point at which the injection is completed with respect to the travel of thepiston in its cylinder. Three functions are variable, the point at which actuating movement, of the cam begins, with respect to the point thereon where the actuating movement ends, the pointat which the plunger stroke terminates with respect to the'point where the stroke starts, and the point at which the injection into the cylinder begins with respectl to the constant point where it ends.

With the above and other ends in view the invention is more fully disclosed with reference to the accompanying drawings, in which Figure 1 is a vertical cross section of the in- `iector;

Figs. 2 and 3 are diagrammatic views illustrating different stages in operation;

Fig. 4 is a detail of the operating cam;

Fig. 5 is a fragmentary elevation of a detail;

Fig. 6 is a diagrammatic view illustrating the movements of the plunger;

Fig. 7 is a diagrammatic view illustrating the movements of the piston and crank shaft;

Fig. 8 is 'a vertical cross section of a modied stroke adjuster, and

Fig. 9 is a view corresponding to Fig. 8 and illustrating another stage in operation.

Like characters of reference are employed throughout to designate corresponding parts.

The injector device comprisesa crank case I having a body 2 secured thereon by any suitable securing means. Rotatably supported in the crank case I is a cam shaft r3 having a cam 4 secured or formed thereon. The cam shaft 3 is adapted to be connected to the crank shaft of an internal combustion engine to rotate in unison therewith in the manner well known in the art and therefore not illustrated here.

In the body 2 there is provided a fuel injector mechanism of the type shown and claimed in my copending application Serial No. 615,624, led June 6, 1932, and allowed October 18, 1934. As illustrated, the body 2 is formed with a fuel reservoir 5 having a fuel supply line 6 connected thereto. A sleeve 1 extends through the top of the body 2, through the reservoir 5, and through a substantial portion of the body 2. The upper end of the reservoir 5 is sealed by a ring 8 clamped by a nut 9 on the exposed portion of the sleeve 1. Attached to the upper end of the sleeve 1 is a line I0, held by a coupling element I2 and leading to the injection nozzle at the cylinder of an engine in a manner well known in the art and therefore not illustrated here.

On the lower end of the sleeve 'I is screwed another sleeve I3 having a flange I4 bearing upwardly against a shoulder I5 formed in the body 2. A plunger I6 is slidably mounted in the lower part of the sleeve I3 and extends upwardly through the sleeve 1 beyond the bottom of the reservoir 5.4 The lower end of the plunger is rounded at I1 and rests upon an arm I8 which in turn is supported in a manner to be presently described. The lower end of the plunger is further formed with a spring seat I9 receiving the lower end of avspring 20 which has its upper end bearing against the shoulder I4 to hold the plunger normally in engagement with the arm I8. y

In the upper end of the plunger I6 is formed a cavity 2| in which is mounted an upwardly opening poppet valve 22 resting on a spring 23. Ports 24 are drilled through the sleeve 1 at the reservoir 5 to register with ports 25 in the plunger I6 and communicating with the cavity 2|.

A plug 2'6 is mounted in the sleeve 1 at a distance above the upper end of the plunger I6 and has a series of passages 21 drilled therethrough. A poppet valve 28 is slidably mounted in the plug and is adapted to obstruct the passages 21 when in its lowered position.- A spring 29 bearing upon this' valve normally holds l@ in its closed position.

A journal shaft 3o is mounted 1n the bbttom of the crank case I in parallel relation to the cam shaft 3, and on the shaft 30 isV journalled a follower 3I. The follower 3| is preferably in the form of a frame having its sides straddling the cam 4, similar to the showing in the above re-l ferred to co-pending application. The follower 3| carries a roller 32 engageable with the cam 4 and in the normal position shown in Fig. 1 the axes of the cam 4 and roller 22 are in the same horizontal plane. The upper end of the follower 3| carries another roller 33, the center of which is normally in a vertical line with the center of the shaft 38. A spring 34 engages the follower 3| and normally urges pivotal movement thereof in a direction to maintain the roller 32 in engagement with the cam 4. p

The arm I8 has one end pivotally attached to a slidable block 35, supported in a guide 36, and having a slot 31 therein receiving an eccentric 38 on a shaft 39 so that by rotating the shaft 39 the block may be caused to slide in one direction. Any suitable manual means may be employed to rotate the shaft 39.

The arm I8, on its lower side, is provided with an arcuate surface 40, the ends of which are illustrated in Figs. 1 and 5 by radial lines 4I and 42 which extend from the center of the shaft 38. The surface 40 is therefore concentric with the path of movement of the roller 33 carried by the lfollower 3| when the arm I8 is in the position shown in Fig. 1, which is the inoperative position. Therefore, when the follower 3| is rocked by the cam 4, from the position shown in full lines in Fig. 1 to' that shown in the dotted lines, the roller 33 contacts the arcuate surface 40 and the arm I8 is supported in a stationary position by the moving roller 33.

'I'he lower surface of the armI I8 has an arcuate surface 43 beginning at the terminal 42 of the surface 4|| and having a radius c '.isiderably less than the radius of the arcuate surface 40. The upper surface of the arm I8 has an arcuate surface 44 engaged by the rounded portion I1 on the plunger and terminating in a shoulder 45. The arcuate surfaces 40 and 44 are concentric and the length of the surface 40, which is longer than the surface 44, is defined by the radial lines 4| and 42 in Figs. 1 and 5. Both arcuate surfaces 40' and 44 start at the radial line 4|, the surface 40 terminates at the line 42, and the surface 44 terminates at the line 42 shown on Fig. 5 only. These lines 4| and 42 also serve. to designate the length of the rocking movemen'. of the rocking arm 3| on Fig. 1.

As shown in Fig. 2 the arm I8 has been moved to a position which provides for the full length plunger stroke. During such full length stroke the cam 4 engages the roller 32 to rock the follower |8 from the position shown by the dot and dash line 46 to the position indicated by dotted center line 41. During such movement the roller 3 3 rides against the arcuate surface 48 until it reaches the point indicated by the radial line 48. During this movement no appreciable movement of the arm I8 will take place. However, a very slight movement will be present, due to the fact that the arcuate surface is no longer concentric with the follower 3|, but this movement is so small that the check valves do not function and the plunger does not eject any fuel. After the roller 35 passes the position indicated by the line 48 it will ride against the arcuate surface 43 and will cause the arm I8 to pivot .to the dotted line position shown in Fig. 2. The full line position of the plunger I6 .in Fig. 2v illustrates it at the limit of its down stroke and the dotted line position illustrates the limit of its upward stroke.

It will be noted that the movement of the arm I8 from the position shown in Fig. 1 to that shown in Fig. 2 does not disturb the plunger I6 due to the fact that during such movement, that part of the arm I8 which is between vthe roller 33 and the plunger I6 is of uniform thickness because the two surfaces 48 and 44 are concentric. Thus, the plunger I6 always comesto rest at the same point regardless of the position of adjustment of gages the roller 32, the roller 33 and the follow- `er will be moved from the position indicated'by the line 46 to the position indicated by the line 48 in Fig. 2. lWhen the surface ofV thecam between lines 58 and 5I progressively acts upon the roller 32 the roller 33 and the follower will move from the position designated by the line 48 in Fig. 2 to that designated by the line 81, which, as described above. results in the ejection stroke of the plunger. Therefore, according to the example shown, twenty degrees of angular l stroke.

movement of the cam 4 is required to cause the full injection stroke o`f the plunger.

Referring to Fig. 3 line 52 designates the center line of the follower 3| in its normal inoperative position. The arm I8, in this figure, is positioned approximately midway `between the positions illustrated in Figs. 1 and 2, which position provides for approximately one half of a stroke of the plunger. With the parts as shown in Fig. 3 the roller 33 will ride against the arcuate surface 48 until it reaches the position shown in full lines and indicated by the line 53.. During this movement no appreciable movement of the lever I8 and plunger I6 will take place for the reasons above pointed out. From the position designated by the line 53 to that designated by the line`54 the fuel ejection stroke of the plunger is caused to take place. However, it will be noted that the point on the cam 8 at which movement of the arm I8 starts, designated by the line 55, is approximately ten degrees from the point 5I which' represents the end of the injection It becomes apparent, therefore, that as the mechanism functions to vary the length of the stroke of the. plunger I6 the point at which the stroke terminates always remains constant with relation to the position of the cam inasmuch as it terminates when the point 5I engages the roller 32. i

The high part of the cam extends through approximately thirty-four degrees in order to hold the plunger stationary at the end of its pumping i stroke for a sufficient length of time to permit the check valves in the injector to react.

The length of the `plunger stroke may be inlfinitely varied between the examples illustrated and described, and throughout all these adjustments the plunger always comes to rest at a constant point. In Fig. 6 the plunger i6 is diagrammatically illustrated as being at the point from which the ejection stroke starts, and this point is designated by the line 88. In completing a full length stroke the plunger I8 moves from the' point designated by the line 68 tothe point designated.

by the line 6I, and after the cam 4 has been rotated until the low part thereof engages the follower the spring 28 will return the plunger to the point designated by the line 88. Inthe event that the arm I8 has been positioned as in Fig. 3 the plunger movement will start at the point designated by the line 68 and Will terminate at the point designated bythe line 62, thus providing Afor a half stroke. A quarter stroke of the plunger starts at the point designated by line 68 and terminates' at the point designated by the line 83, and a three quarterv strokev starts-at the line 88 and terminates at the line'64.

Referring to the diagram in Fig. '7, 65 designatesa piston of an engine and'66 its crank. vThe line 8l designates the point in the movement of the piston that will'be reached when the crank 66 is at its dead center. The line 68 designates the point in the movement of the cam where the injection of fuel intothe cylinder is to be completed.- This point will be ydetermini-2d by the characteristics of individual engines. When the crank 65 is in the position designated by the line y 89 the piston 65 will be at the position indicated by the line 68, the cam 4 will be in a position where the point 5I is engaging the follower. and the plunger lIii will have been moved from the point 68 to the point 6I and the full injection will have been completed. While this'full injection is being completed and the cam 4 is moving from the point 58 to the point 5I the crank will have moved from the point designated by theline 18 and the piston will have moved from the point designated by the line 1 I. In the event of a half injection the injection will start when the crank` crank is at the point 69 and the piston at the point 88. The quarter injection starting point is indicated by the line 14 relative to the crank and the line I5 relativeto the piston. The threequarter injection point is indicated at "E8 on the crank and at 'Il on the piston. It becomes apparent, therefore, that all injections end when the crank and 'piston are at definite points'in their travel and that short injections are completed during a shorter travel of the crank and piston than the travel thereof during a full injection.

In Figures 8 and 9 there is illustrated a modifled construction of the stroke regulating mechanism. In this form the crank ycase is designated Ia, the cam shaft 3a, the cam 4a and the plunger Ita. In the crank case is a journal shaft 38a supporting a follower 3i a bearing rollers 32a. and 33a. These elements are constructed the same as the elements described above, in detail and their functions are identical. v

Between the roller 32a and the plunger 08a extends an arm I8a having concentric arcuate surfaces 48a and 44a whose centers coincide with the center of movement of the follower. The arm lila is pivotally connected to a lever 88 having one end pvotally received on the journal shaft 3a. The lever 88 has an armf8I provided with a slot 82 receiving an eccentric 83 on a shaft 84 so that by rotating the shaft 84 the eccentric moves the lever 88 from the position shown in Fig. 8 to that shown in Fig. 9.

As shown in Fig. 1, the roller'33a'in moving from the position shown in full lines to that shown in'dotted lines does not cause any movement of the arm I8a. When the arm 18a is positioned as in Fig. 9 movement of the roller 33a from the position shown in full lines to that shown in dotted lines does not cause any movement ofthe arm I8a, but the position shown in dotted lines is approximately half the travel of the roller 33a and therefore when the roller continues from this point it engages the arcuate surface 43a to cause pivotal movement of the arm Isa. It `will be noted in this form that as the arm lila moves between the positions shown in Figs. 8 and 9 that the lever 80 supports and guides the same so that the two arcuate surfaces 40a and a always remain concentric with the journal shaft 30a. Thus the slight movement presented during the initial movement of the follower 3Ia does not cause any movement of the arm |811. in the manner of the slight, but inappreciable, movement of the arm I8 due to the fact that when it is moved from itsposition shown in Fig. 1 the surface 40.

no longer remains concentric with the shaft 30.

Although specific embodiments of the present inventionare illustrated and described it will be understood that various changes may be made within the scope of the appended claims without departing from the spirit of the invention. For example, the exact number of degrees mentioned during the description, although found to be desirable 'and practical, were employed for illustrative purposes and the invention is not limited thereto.

What I claim is:-

1. In a fuel injector, a plunger, a rocker arm pivoted at one end, means for rocking said arm t cause swinging movement of the free end thereof through a predetermined arc, an operating arm interposed between the swinging end of said arm and said plunger and adapted to be moved by said swinging end to impart movement to said plunger, said operating arm having an arcuate portion of uniform thickness with one of the arcuate surfaces thereof engaged by said swinging end and the other arcuate surface engaged by said plunger, the two arcuate surfaces having a common 'center of curvature, said operating arm having a cam surface merging with the arcuate surface engaged by said rocker arm, means supporting said operating arm, said common center of curvature being coincident with the axis of swinging movement of said rocker arm, and means for adjustably moving said operating arm with respect to said rocker arm.

2. In a fuel injector, a plunger, a rocker arm pivoted at one end, means for rocking said arm to cause swinging movement of the free end thereof through a predetermined arc, an operating arm interposed between the swinging end of said arm and said plunger and adapted to be moved by said swinging end to impart movement to said plunger, said operating arm having an arcuate surface engaged by said swinging end corresponding in length to the arc of swinging movement thereof and an arcuate surface en-` gaged `by said plunger and having a common center of curvature with the rst named arcuate surface, said operating arm having another arcuate surface at a terminal of the arcuate surface engaged by said rocker arm, the radius of curvature of said last named surface being shorter than the radii of the first two arcuate surfaces, means 

